There are a handful of places in the world where
europium-containing ore is mined, but deposits of the rare
element europium
(atomic number 63) are in short supply. Few people cared until
the invention of the television.

Early color television programs were barely colored: The blues
were muted, yellows appeared somewhat bleached out and whites
were dingy and grayish. The reason? Nobody could find a way to
reproduce a strong, rich red color, so the other colors were
toned down to maintain some balance.

Then, once it was discovered that europium reproduced a robust
red in television (And later, computer) screens, the scramble for
europium supplies was on. Mines in China, Russia and a small mine
in California supply most of the world's europium.

First discovered in 1879, scandium
(atomic number 21) was named for Scandinavia by chemist Lars
Fredrik Nilson. Though it's fairly common in the Earth's crust,
nobody had any real use for this silvery metal until about 100
years after its discovery.

But in the 1970s, metallurgists found that aluminum-scandium
alloys are strong and lightweight, making it useful in aerospace
components. It wasn't long before sporting-equipment
manufacturers started using the alloys in everything from
baseball bats to lacrosse sticks.

Beryllium (Be)

In Isaac Asimov's sci-fi story "Sucker Bait," scientists struggle
to understand why all the colonists of the planet known as Junior
died after settling on its surface. Finally, one mutinous
renegade realizes that high levels of beryllium in the soil
caused the colonists to slowly die of berylliosis.

The dangers of beryllium
aren't just the stuff of fiction, however: The element (atomic
number 4) is recognized as a carcinogen by the International
Agency for Research on Cancer.In another form, however, beryllium
is highly desirable, even priceless. When combined with trace
amounts of chromium, beryllium takes on a beautiful green hue as
the gemstone commonly known as the emerald.

Gallium (Ga)

Few elements are weirder than gallium : A
relatively soft, glittering metal, it's widely used today in
semiconductors and other electronics, as well as in the
pharmaceutical industry.

But in years past, gallium (atomic number 31) was a key part of a
favorite parlor trick for magicians because it melts when it's
just slightly warmer than room temperature. Thus, spoons that are
made of gallium look normal, but when dipped into a cup of hot
tea will instantly dissolve. Even holding a gallium spoon in your
hand too long will create a drippy, metallic mess.

Tellurium (Te)

Tellurium,
a silvery-white metal first discovered in Transylvania, is often
used in solar panels, computer memory chips and rewritable
optical discs. Its name comes from the Latin word for earth
(tellus).

Tellurium (atomic number 52) is considered by most experts to be
mildly toxic, though it's unusual to find someone who has
suffered serious harm from it. How to tell if someone has been
exposed to high levels of tellurium? As their body metabolizes
telluride, their breath will have a pungent, garlic-like odor —
as befits an element first found in Dracula's legendary homeland.

"Hoarding gold is for libertarians. Bitcoin mining is for nerds,"
wrote Jonathon Keats in Wired.
"Really adventurous investors — especially fans of the stranger
stretches of the periodic table — ought to consider stockpiling
something more intense, like industrially valuable exotic
elements."

High on the list of rare, valuable elements is dysprosium
(atomic number 66), which is named after the ancient Greek
dysprositos, meaning "hard to get," appropriately
enough. The soft, metallic substance is in big demand for
electric motors, especially those in electric vehicles and wind
turbines, which has earned dysprosium a place on the U.S.
Department of Energy's list of critical materials for the green
economy.